The present invention relates to a wire-bonded semiconductor device, and more particularly to a wire-bonded semiconductor device with staggeringly aligned wire-bonding pads and a method of wire-bonding a semiconductor device.
A typical one of the conventional wire-bonded semiconductor device will be described with reference to FIGS. 1A and 1B. FIG. 1A is a fragmentary cross sectional elevation view illustrative of a wire-bonded semiconductor device packaged in a sealing resin material. FIG. 1B is a partially enlarged plane view illustrative of a wire-bonded semiconductor device of FIG. 1A. A semiconductor device 23 is placed on an island 28. The semiconductor device 23 is square-shaped and has a peripheral area on which bonding electrode pads 24 are provided to align along each side of the square-shaped semiconductor device 23. Inner leads 21 are provided which extend outwardly in radial directions. Inside end portions of the inner leads 21 are spaced apart from the outside edges of the semiconductor device 23. The positions of the inside edges of the inner leads 21 are different in distance to the outside edge of the semiconductor device 23 between adjacent two inner leads 21 so that the inside edges of the inner leads 21 are staggeringly aligned. Namely, one of the adjacent two inner leads 21 has an inner-positioned inside edge which is thus positioned closer to the peripheral edge of the semiconductor device 1 than outer-positioned inside edge of the remaining one of the adjacent two inner leads 21 so that the inner-positioned inside edges and the outer-positioned inside edges are alternately aligned. Inside bonding pads 21a are provided on the inner-positioned inside edges of the inner leads 21 whilst the outside bonding pads 21b are provided on the outer-positioned inside edges of the inner leads 21. A ridged taping material 22 is provided which extends along between alignments of the inside and outside bonding pads 21a and 21b so that the inside and outside bonding pads 21a and 21b are separated by the ridged taping material 22. The bonding electrode pads 24 of the semiconductor device 1 are bonded via bonding-wires 25 to the inside and outside bonding pads 21a and 21b of the inner leads 21. The wire-bonded semiconductor device 23, the bonding-wires 25 and the island 28 are sealed with a sealing resin material 30.
As illustrated in FIG. 1B, a distance between the adjacent two inner leads 21 is made narrow gradually in the inside direction toward the semiconductor device 23 so that the inner leads 21 become closer to each other as the position is closer to the peripheral edge of the semiconductor device 1. The ridged taping material 22 provided between the alignments of the inside and outside bonding pads 21a and 21b hold the inner-positioned inside edges and prevent the inner-positioned inside edges from dislocation. The inner-positioned inside edges of the inner leads 21 is thus made free of dislocation. This means that the provision of the ridged taping material 22 prevents contacts between the inner-positioned inside edges of the inner leads 21. This means that the provision of the ridged taping material 22 allows the inner-positioned inside edges of the inner leads 21 to be made closer to the peripheral edge of the semiconductor device 23. This firer means that the provision of the ridged taping material 22 prevents contacts between the inner-positioned inside edges of the inner leads 21, even the pitch of the inner-positioned inside edges of the inner leads 21 is extremely narrow. If the inner-positioned inside edges of the inner leads 21 have the closer positions to the peripheral edge of the semiconductor device 1, this means that the bonding-wires 25 are short so that the bonding-wires 25 have no remarkable bending or dangling. The longer bonding-wires 25 connecting the bonding electrode pads 24 to the outside bonding pads 21b of the inner leads 21 is arched to cross over the ridged taping material 22 whereby remarkable bending or dangling of the longer bonding-wires 25 are prevented. This contributes to prevent contacts between the inner-positioned inside edges of the inner leads 21 or between the longer bonding-wire 25 and adjacent inner-positioned inside potion of the inner lead 21.
The above-described conventional wire-bonded semiconductor device, however, has disadvantages as follows. At the comer of the semiconductor device 23, the adjacent longer and shorter bonding wires are likely to be contacted to form a short circuit because the outside and inside bonding pads 21a and 21b are concentrated in the vicinity of the corner of the semiconductor device 1 and because the distances between the adjacent bonding electrode pads 24 and between the adjacent bonding-wires 25 are narrower in the vicinity of the comer of the semiconductor device 1.
Another disadvantage of the above-described conventional wire-bonded semiconductor device is in a possibility of displacement of the arched center portion of the bonding-wires 25, particularly the longer bonding-wires 25 caused by pressures of molten sealing resin material 30, when the semiconductor device 23 is packaged with the sealing resin material 30.
In place of the wire-bonded semiconductor device, a tape-automated bonding structure has been known. Notwithstanding, the tape-automated bonding structure may raise another disadvantage in higher manufacturing cost than the wire-bonded semiconductor device.
In the above circumstances, it had been required to develop a novel wire-bonding structure of a wire-bonded semiconductor device free from the above disadvantages.